Power train

ABSTRACT

Power train for amphibious vehicle comprises engine aligned with longitudinal vehicle axis, transmission, and power take off mounted between engine and transmission. At least one marine propulsion unit mounted at the rear of the vehicle, is driven by shaft which runs alongside the transmission. Either transmission is offset to axis, and marine propulsion unit is on axis; or transmission is on axis, and the marine propulsion units are offset to axis. The driven road wheels may be the front wheels, the rear wheels, or all four. The engine may be at the front of the vehicle and the transmission at the back. Alternatively, the transmission may drive forward to a differential mounted adjacent to the engine sump, with wheel drive shaft passing through said pump.

BACKGROUND OF THE INVENTION

The present invention relates to a power train suitable for use in anamphibious vehicle capable of travel on land and water, particularly toa power train in which a conventional in-line automotive engine andtransmission arrangement is adapted to drive at least some of the wheelsand a marine propulsion means of an amphibious vehicle. The inventionalso relates to an amphibious vehicle having such a power train.

In a known automotive power train arrangement, an engine having acrankshaft is positioned such that the crankshaft is in-line with thelongitudinal axis of the vehicle. The engine drives a transmission whichis arranged in line with and behind the engine. Often, the transmissionhas an integral differential which is connected by axle shafts to drivea pair of road wheels of the vehicle. This arrangement is commonly knownas a transaxle drive and has been employed in front engine, rear engineand mid engine power train layouts.

The in-line power train, and in particular the transaxle front wheeldrive arrangement is currently used by several large car manufacturersin the production of larger private passenger vehicles and is thereforeproduced in relatively high volumes, which makes the arrangement mostprocurable for use in an amphibious vehicle. In choosing a power trainfor a specialized low volume production vehicle, such as an amphibiousvehicle, availability is an important factor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a power train for anamphibious vehicle, in which a conventional in-line engine andtransmission are utilized and adapted. It is a further object of theinvention to provide an amphibious vehicle having such a power train.

In accordance with a first aspect of the invention, there is provided apower train for an amphibious vehicle, which power train comprises anengine adapted for mounting in the vehicle such that a crankshaft of theengine is substantially in alignment with a longitudinal axis of thevehicle, a transmission, and a power take off positioned in the driveline between the engine and the transmission, characterized in that thepower take off is adapted to drive at least one marine propulsion unitlocated at the rear of the amphibious vehicle by means of a shaft whichruns alongside the transmission.

In a preferred embodiment, a transfer drive is provided between theengine and the transmission, the transfer drive being adapted totransfer drive from the crankshaft of the engine to the transmission andto a drive shaft for the marine propulsion means, the drive shaft forthe marine propulsion means being in axial alignment, or substantiallyso, with the crankshaft of the engine, and the transmission being offsetrelative to the crankshaft. The transfer drive may comprise a drivingsprocket offset arranged for rotation with the crankshaft of the engineand a driven sprocket offset from the crankshaft, the driving and drivensprockets being drivingly interconnected by a toothed belt or chain. Thedriving sprocket may be mounted to a first shaft which is connected tothe crankshaft of the engine, the first shaft being adapted to drive thedrive shaft for the marine propulsion unit. The first shaft may beconnected to the drive shaft for the marine propulsion unit by adecoupler. In a preferred arrangement, the driven sprocket is arrangedto drive a second shaft which provides an input to the transmission. Thesecond shaft may be connected to an input shaft of the transmission by adrive coupling unit such as a fiction clutch or a fluid coupling.

In an alternative preferred embodiment, the transmission is adapted tobe mounted such that it is substantially in axial alignment with theaxis of the crankshaft with the center line of the at least one marinepropulsion unit being located parallel to and offset from thelongitudinal axis of the vehicle. In such an arrangement, the power takeoff may be adapted to drive two marine propulsion units located at therear of the amphibious vehicle, the respective center lines of themarine propulsion units being located parallel to and offset from thelongitudinal axis of the amphibious vehicle on opposite sides thereof.The power take off may be adapted to drive the two marine propulsionunits by means of shafts which run along opposite sides of thetransmission.

Preferably, the engine and transmission are adapted to be positionedtowards the front of the amphibious vehicle and to provide drive to atleast the front wheels of the vehicle.

Alternatively, the engine and transmission are adapted to be positionedtowards the rear of the vehicle and to provide drive to at least therear wheels of the vehicle.

In a further alternative embodiment, the engine is adapted to bepositioned towards the front of the vehicle and the transmission isadapted to be positioned towards the rear of the vehicle and to providedrive to at least the rear wheels of the vehicle.

Preferably, the transmission is a transaxle unit integral gearbox anddifferential. Alternatively, the transmission may have an output locatedto one side thereof and which drives a differential positioned adjacenta sump of the engine.

A further power take off may be provided such that the power train canprovide drive to both the front and the rear wheels of the vehicle.

Preferably, the shaft or shafts which run alongside the transmission areadapted to be mounted in alignment with or parallel to the longitudinalaxis of the vehicle.

In accordance with a second aspect of the invention, there is providedan amphibious vehicle, characterized in that it comprises a power trainin accordance with the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the invention will now be described, by way ofexample only, with reference to the following drawings in which:

FIG. 1 is a schematic plan view of a view having a conventional powertrain arrangement;

FIG. 2 is a schematic plan view of an amphibious vehicle having a powertrain in accordance with a first embodiment of the invention;

FIG. 3 is a side view, partially in section, of the power train of FIG.2;

FIG. 4 is a section through a transfer drive of the power train of FIGS.2 and 3 as viewed looking in the direction of the engine;

FIG. 5 is a view similar to that of FIG. 2 but showing a secondembodiment of a power train in accordance with the invention;

FIG. 6 is a view similar to that of FIG. 2 but showing a thirdembodiment of a power train in accordance with the invention;

FIG. 7 is a view similar to that of FIG. 2 but showing a fourthembodiment of a power train in accordance with the invention;

FIG. 8 is a view similar to that of FIG. 2 but showing a fifthembodiment of a power train in accordance with the invention;

FIG. 9 is a view similar to that of FIG. 2 but showing a sixthembodiment of a power train in accordance with the invention; and

FIG. 10 is a view similar to that of FIG. 2 but showing a seventhembodiment of a power train in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Common reference numerals are used throughout to denote parts in commonbetween the several embodiments.

Referring firstly to FIG. 1, a conventional in-line power trainarrangement is shown driving the front wheels 14,16 of a vehicle 12. Anengine is positioned forward of the front wheels 14,16 with thecrankshaft (not shown) of the engine 18 in axial alignment with thecentral axis 20 of the vehicle 12. A transaxle drive unit, indicatedgenerally at 11, comprises a transmission or gearbox 22 mounted in linewith the engine 18 and an integral differential 24, positioned at thebottom of the transmission 22. Axle shafts 26, 28 drive the front wheels14,16 of the vehicle from the differential 24. The rear wheels 30, 32 ofthe vehicle 12 are not driven.

A first embodiment of the invention will now be described with referenceto FIGS. 2 to 4.

A power train, indicated generally at 10, comprises an engine 18 whichis mounted towards the rear of an amphibious vehicle 34, forward of thecenter line of the rear wheels 30, 32, with the crankshaft 19 (partiallyshown in FIG. 3) of the engine 18 in axial alignment with thelongitudinal axis 20 of the vehicle. A transfer drive, generallyindicated at 36 and shown in more detail in FIGS. 3 and 4, is housed ina chaincase 38 mounted to the engine 18. A transaxle drive unit,generally indicated at 11, including a transmission or gearbox 22 anddifferential 24 is mounted to the chaincase 38. The power train 10 alsocomprises a marine propulsion unit in the form of a water jet 40. Thetransaxle drive 11 and the water jet 40 are both driven by the engine 18through the transfer drive 36.

The transfer drive 36 comprises a driving sprocket 42 mounted on adriving shaft 44, which is connected to the crankshaft 19 of the engine18. A further sprocket 46 is offset laterally and vertically relative tothe shaft 44 and is driven from the driving sprocket 42 by means of atoothed belt or chain 48. The sprocket 46 is mounted on and drives ashaft 50, which provides an input to the transaxle drive unit 11 as willbe described below. Alternatively, gears may be used to transfer drivefrom the driving shaft 44 to the driven shaft 50.

Drive for the water jet 40 16 taken from the driving shaft 44 of thetransfer drive 36. The driving shaft 44 is connected to a drive shaft 54of the water jet by A decoupler 52. The drive shaft 54 of the water jetis substantially in axial alignment with the crankshaft 19 of the engineand so with the longitudinal axis 20 of the vehicle. An impeller 56 ismounted on the shaft 54. Whilst it is preferred that a decoupler 52 beincorporated in the drive line between the engine and the marinepropulsion unit to be enable drive to the marine propulsion unit to beselectively disengaged when the vehicle is operating in road mode, thisis not essential and the decoupler 52 can omitted if desired.

The transaxle drive unit 11 is driven by the drive shaft 50 via afriction clutch 65 mounted at the front of the transmission 22. Thefriction clutch 65 is a conventional friction clutch of the typecommonly used in automotive vehicles and so need not be described indetail. The clutch 65 is mounted to a flywheel or counter pressure plate64 which is arranged for rotation with the drive shaft 50. The clutch 65transfers drive from the flywheel 64 to an input shaft (not shown) ofthe transmission 22 via a driven plate (not shown) in a conventionalmanner.

In an alternative embodiment where the transmission 22 comprises anautomatic gearbox, the friction clutch 65 can be replaced by a fluidcoupling such as a torque converter in a manner well known in the art.

It will be noted that the transaxle drive unit 11 is offset relative tothe crankshaft 19 of the engine such that the input shaft (not shown) ofthe transmission 22 is in axial alignment with the shaft 50. The offsetposition of the transaxle drive unit 11 ensures that the drive for thewater jet can be aligned with the crankshaft of the engine and so withthe longitudinal axis of the vehicle. This simplifies the drivearrangement for the single water jet which is preferably positionedcentrally at the rear of the vehicle.

The differential 24 of the transaxle unit 11, drives the rear wheels30,32 via axle shafts 58, 60. The axle shaft 58, which drives the lefthand (as viewed) rear wheel 32, is connected directly to thedifferential. However, because the transaxle drive unit is offset to theleft, as viewed, the axle shaft 60, which drives the right hand (asviewed) rear wheel 30, is connected to the differential through a relayshaft 62. The relay shaft 62 passes perpendicular to the drive shaft 54of the water jet unit 40, and may be located above or below the shaft 54depending on the particular geometry of the vehicle 34.

Referring now to FIG. 5, a second embodiment in accordance with theinvention will be described.

FIG. 5 shows an amphibious vehicle 134 having a power train 110 which issimilar to the power train 10 of the vehicle 34 described above inrelation to FIGS. 2 to 4. The main differences being that the engine 18,transfer drive 36 and transaxle drive unit 11 are located towards thefront of the vehicle in order to drive the front wheels 14, 16, and inthat the optional decoupler 52 is connected to a propeller shaft 68 withcentre bearing 67 which drives the rear mounted water jet 40.

The rear wheels 30, 32 of the vehicle 66 are not driven, however, ifdesired a power take off (not shown) could be provided from thetransaxle drive unit 11 to drive a further differential (not shown) fordriving the rear wheels 30, 32.

As discussed above, the use of a transfer drive between an in-lineengine and a transmission enables the transmission to be offset relativeto the axis of the crankshaft, such that drive to a marine propulsionunit can be provided in axial alignment with the longitudinal axis ofthe vehicle. This has significant advantages in the design layout of anamphibious vehicle while enabling conventional and readily availablein-line engine and transmission drive units to be utilized. Thisarrangement is particularly suited to use with an in-line engine andtransaxle power train unit.

FIG. 6 shows a third embodiment of a power train 210 in accordance withthe invention. The power train 210 comprises an engine 18 mountedtowards the rear of an amphibious vehicle 234 with the crankshaft (notshown) substantially in-line with the longitudinal axis (not shown) ofthe vehicle. An in-line transaxle unit 11 is provided behind the engineand drives the rear wheels 30, 32 of the vehicle in a conventionalmanner.

The power train 210 also has two marine propulsion units 40A, 40B at therear of the vehicle. The marine propulsion units 40A, 40B are arrangedsuch that their respective center lines are parallel to and offset, onopposite sides, from the longitudinal axis of the vehicle. A sandwichpower take off 70 is provided between the engine and the transaxle unit11 and drives the marine propulsion units via shafts 72, 74 which runalong opposite sides of the transaxle unit 11.

The power take off 70 has a pair of output shafts 75, 76 driven by thecrankshaft of the engine 18, and is enclosed by a gear case 9. Theoutput shafts 75 and 76 are shown parallel to and on either side of thetransaxle 11 and are coupled to the drive shafts 72 and 74 respectivelywhich run rearward and are connected in driveable connection torespective marine propulsion units 40A and 40B. The marine propulsion40A, 40B may be water jets as shown here or may be screw propellers orany other suitable marine propulsion system.

A fourth embodiment of a power train 310, in accordance with theinvention is shown in FIG. 7. The power train 310 is similar to thepower train 210 shown in FIG. 6 except that the engine and transaxle aremounted towards the front of the vehicle334 such that the transaxle unit11 drives the front wheels 14, 16 of the vehicle. Because the engine andtransaxle are mounted towards the front of the vehicle, it is necessaryfor the sandwich power takeoff 70 to drive the marine propulsion units40A, 40B through extended drive shafts 72′, 74′ with center bearings 67′which run along opposite sides of the transaxle 11. The transaxle 11transmits drive to the front wheels 14, 16 via axle shafts 26 and 28 inconventional automotive manner.

A fifth embodiment of a power train 410 is shown in FIG. 8. Power train410 is similar to power train 310 described above, but includes drive torear wheels 30, 32 by a power take-off from the rear end of transmission411, through shaft 69 and optional center differential 31, to reardifferential 424 and rear axle drive shafts 27 and 29. A decoupler (notshown) may be included between transmission 411 and shaft 69 to enabledrive to the rear wheels to disconnected.

A sixth embodiment of a power train 510 is shown in FIG. 9. Power train510 is similar to the power trains 210 and 310 described above andcomprises an in-line engine 18 and transmission 11′, with a power takeoff 70 in the drive line between the engine and the transmission andwhich drives a pair of marine propulsion units 40A, 40B at the rear ofthe vehicle 534. The marine propulsion units having respective centerlines which are parallel to and offset on opposite sides from thelongitudinal axis of the vehicle. In this embodiment, however, theengine is positioned towards the front of the vehicle, while thetransmission 11′ is located towards the rear of the vehicle to drive therear wheels. Drive is transmitted from the engine to the transmission bymeans of a shaft 80 which may be a propeller shaft.

In the embodiment shown, the transmission 11′ is a transaxle having anintegral differential 24 located in-line and rearwardly of an output endof the gearbox 22. The differential drives the rear wheels of thevehicle through axle shafts 58, 60 in a conventional manner. Thetransmission could, however, be a transaxle of the type shown in FIGS. 1to 8 in which the differential is located at the bottom of the gearbox22.

A final embodiment of the invention is shown in FIG. 10. A power train610 comprises an in-line engine 18 and transmission 11″ located towardsthe rear of an amphibious vehicle 634. A power take off 70 between theengine 18 and transmission 11″ drives a pair of marine propulsion units40A, 40B by means of drive shafts 72″, 74″ which run along oppositesides of the transmission. The marine propulsion units having respectivecenter lines which are parallel to and offset on opposite sides from thelongitudinal axis of the vehicle.

The transmission 11″ has an output 82 which is located to one side ofthe transmission and which extends forwardly to drive a differential 24″positioned adjacent to one side of the sump of the engine 18. Thedifferential 24″ drives the right hand rear wheel 30 of the vehicle viaa relay shaft 84 and an axle shaft 60. The differential drives the lefthand rear wheel 32 directly via a further axle shaft 58 in aconventional manner. The relay shaft 84 may pass along one side of thesump, below the sump or through a tunnel formed in the sump as isconvenient to the design of the vehicle.

If required, the engine, power take off and transmission of power train610 could be positioned towards the front of the vehicle with thedifferential 24″ driving the front wheels of the vehicle. In this case,the shafts, 72″, 74″ which drive the marine propulsion units would haveto be extended in a manner similar to the shafts 72′, 74′ shown in theFIG. 7 embodiment.

In all of the embodiments described above in relation to FIGS. 6 to 10,rather than having two offset marine propulsion units, the power trainmay comprise a single water jet at the rear of the vehicle, the centerline of the water jet being located parallel to and offset from thecenter line of the amphibious vehicle.

Whereas the invention has been described in relation to what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not limited to thedisclosed arrangements but rather is intended to cover variousmodifications and equivalent constructions included within the spirit ofthe invention. For example, the water jet units may be replaced by anyother suitable marine propulsion means, such as a marine screwpropeller.

What is claimed is:
 1. A power train for an amphibious vehicle, whichpower train comprises: an engine adapted for mounting in the vehiclesuch that a crankshaft of the engine is substantially in alignment witha longitudinal as of the vehicle, a transmission positioned rearwardlyof the engine, and a power take off positioned in the drive line betweenthe engine and the transmission, the power take off being adapted todrive at least one marine propulsion unit located at the rear of theamphibious vehicle by means of a shaft which runs alongside thetransmission, wherein a transfer drive is provided between the engineand the transmission, the transfer drive being adapted to transfer drivefrom the crankshaft of the engine to the transmission and to a driveshaft for the marine propulsion unit, the drive shaft for the marinepropulsion unit being substantially in axial alignment with thecrankshaft of the engine, and the transmission being offset relative tothe crankshaft.
 2. A power train as claimed in claim 1, in which thetransfer drive comprises a driving sprocket arranged for rotation withthe crankshaft of the engine and a driven sprocket offset from thecrankshaft, the driving and driven sprockets being drivinglyinterconnected by a toothed belt or chain.
 3. A power train as claimedin claim 2, in which the driving sprocket is mounted to a first shaftwhich is connected to the crankshaft of the engine, the first shaftbeing adapted to drive the drive shaft for the marine propulsion unit.4. A power train as claimed in claim 3, in which the first shaft isconnected to the drive shaft for the marine propulsion unit by adecoupler.
 5. A power train as claimed in claim 2, in which the drivensprocket is arranged to drive a second shaft which provides an input tothe transmission.
 6. A power train as claimed in claim 5, in which thesecond shaft is connected to an input shaft of the transmission by adrive coupling unit such as a friction clutch or a fluid flywheel.
 7. Apower train as claimed in claim 1, in which the engine and transmissionare adapted to be positioned towards the front of the amphibious vehicleand to provide drive to at least the front wheels of the vehicle.
 8. Anamphibious vehicle, characterized in that the vehicle comprises a powertrain as claimed in claim
 1. 9. A power train for an amphibious vehicle,which power train comprises: an engine adapted for mounting in thevehicle such that a crankshaft of the engine is substantially inalignment with a longitudinal axis of the vehicle, a transmissionpositioned rearwardly of the engine, and a power take off positioned inthe drive line between the engine and the transmission, the power takeoff being adapted to drive at least one marine propulsion unit locatedat the rear of the amphibious vehicle by means of a shaft which runsalongside the transmission, in which the engine and transmission areadapted to be positioned towards the rear of the vehicle and to providedrive to at least the rear wheels of the vehicle.
 10. A power train asclaimed in claim 9, in which a transfer drive is provided between theengine and the transmission, the transfer drive being adapted totransfer drive from the crankshaft of the engine to the transmission andto a drive shaft for a marine propulsion means, the drive shaft for themarine propulsion means being in axial alignment, or substantially so,with the crankshaft of the engine, and the transmission being offsetrelative to the crankshaft.
 11. A power train as claimed in claim 10, inwhich the transfer drive comprises a driving sprocket arranged forrotation with the crankshaft of the engine and a driven sprocket offsetfrom the crankshaft, the driving and driven sprockets being drivinglyinterconnected by a toothed belt or chain.
 12. A power train as claimedin claim 11, in which the driving sprocket is mounted to a first shaftwhich is connected to the crankshaft of the engine, the first shaftbeing adapted to drive the drive shaft for the marine propulsion unit.13. A power train as claimed in claim 12, in which the first shaft isconnected to the drive shaft for the marine propulsion unit by adecoupler.
 14. A power train as claimed in claim 11, in which the drivensprocket is arranged to drive a second shaft which provides an input tothe transmission.
 15. A power train as claimed in claim 14, in which thesecond shaft is connected to an input shaft of the transmission by adrive coupling unit such as a friction clutch or a fluid flywheel.
 16. Apower train as claimed in claim 9, in which the transmission is adaptedto be mounted such that it is substantially in axial alignment with theaxis of the crankshaft, the center line of the at least one marinepropulsion unit being located parallel to and offset from thelongitudinal axis of the vehicle.
 17. A power train as claimed in claim16, in which the power take off is adapted to drive two marinepropulsion units located at the rear of the amphibious vehicle, thecenter lines of the marine propulsion units being located parallel toand offset from the longitudinal axis of the amphibious vehicle onopposite sides thereof.
 18. A power train as claimed in claim 17, inwhich the power take off is adapted to drive the marine propulsion unitsby means of shafts which run along opposite sides of the transmission.19. A power train as claimed in claim 9, in which each said shaft whichruns alongside the transmission is adapted to be mounted substantiallyin alignment with or parallel to the longitudinal axis of the vehicle.20. An amphibious vehicle, characterized in that the vehicle comprises apower train as claimed in claim
 9. 21. A power train for an amphibiousvehicle, which power train comprises: an engine adapted for mounting inthe vehicle such that a crankshaft of the engine is substantially inalignment with a longitudinal axis of the vehicle, a transmissionpositioned rearwardly of the engine and a power take off positioned inthe drive line between the engine and the transmission, the power takeoff being adapted to drive at least one marine propulsion unit locatedat the rear of the amphibious vehicle by means of a shaft which runsalongside the transmission, in which the transmission includes atransaxle unit having an integral gearbox and differential.
 22. A powertrain as claimed in claim 21, in which a transfer drive is providedbetween the engine and the transmission, the transfer drive beingadapted to transfer drive from the crankshaft of the engine to thetransmission and to a drive shaft for a marine propulsion means, thedrive shaft for the marine propulsion means being in substantial axialalignment with the crankshaft of the engine, and the transmission beingoffset relative to the crankshaft.
 23. A power train as claimed in claim22, in which the transfer drive comprises a driving sprocket arrangedfor rotation with the crankshaft of the engine and a driven sprocketoffset from the crankshaft, the driving and driven sprockets beingdrivingly interconnected by a toothed belt or chain.
 24. A power trainas claimed in claim 23, in which the driving sprocket is mounted to afirst shaft which is connected to the crankshaft of the engine, thefirst shaft being adapted to drive the drive shaft for the marinepropulsion unit.
 25. A power train as claimed in claim 24, in which thefirst shaft is connected to the drive shaft for the marine propulsionunit by a decoupler.
 26. A power train as claimed in claim 23, in whichthe driven sprocket is arranged to drive a second shaft which providesan input to the transmission.
 27. A power train as claimed 26, in whichthe second shaft is connected to an input shaft of the transmission by adrive coupling unit such as a friction clutch or a fluid flywheel.
 28. Apower train as claimed in claim 21, in which the transmission is adaptedto be mounted such that it is substantially in axial alignment with theaxis of the crankshaft, the center line of the at least one marinepropulsion unit being located parallel to and offset from thelongitudinal axis of the vehicle.
 29. A power train as claimed in claim28, in which the power take off is adapted to drive two marinepropulsion units located at the rear of the amphibious vehicle, thecenter lines of the marine propulsion units being located parallel toand offset from the longitudinal axis of the amphibious vehicle onopposite sides thereof.
 30. A power train as claimed in claim 29, inwhich the power take off is adapted to drive the marine propulsion unitsby opposite sides of the transmission.
 31. A power train as claimed inclaim 21, in which the engine and transmission are adapted to bepositioned towards the front of the amphibious vehicle and to providedrive to at least the front wheels of the vehicle.
 32. A power train asclaimed in claim 21, in which the engine and transmission are adapted tobe positioned towards the rear of the vehicle and to provide drive to atleast the rear wheels of the vehicle.
 33. A power train as claimed inclaim 21, in which the engine is adapted to be positioned towards thefront of the vehicle and the transmission is adapted to be positionedtowards the rear of the vehicle and to provide drive to at least therear wheels of the vehicle.
 34. A power train as claimed in claim 21, inwhich a further power take off is provided such that the power train canprovide drive to both the front and the rear wheels of the vehicle. 35.A power train as claimed in claim 21, in which each said shaft whichruns alongside the transmission is adapted to be mounted substantiallyin alignment with or parallel to the longitudinal axis of the of thevehicle.
 36. An amphibious vehicle, characterized in that the vehiclecomprises a power train as claimed in claim
 21. 37. A power train for anamphibious vehicle, which power train comprises: an engine adapted formounting in the vehicle such that a crankshaft of the engine issubstantially in alignment with a longitudinal axis of the vehicle, atransmission positioned rearwardly of the engine, and a power take offpositioned in the drive line between the engine and the transmission,the power takeoff being adapted to drive at least one marine propulsionunit located at the rear of the amphibious vehicle by means of a shaftwhich runs alongside the transmission, in which the transmissionincludes an output located to one side thereof, the output being adaptedfor driving a differential positioned adjacent a sump of the engine. 38.A power train as claimed in claim 37, in which the transmission isadapted to be mounted such that it is substantially in axial alignmentwith the axis of the crankshaft, the center line of the at least onemarine propulsion unit being located parallel to and offset from thelongitudinal axis of the vehicle.
 39. A power train as claimed in claim37, in which the engine and transmission are adapted to be positionedtowards the rear of the vehicle and to provide drive to at least therear wheels of the vehicle.
 40. A power train as claimed in claim 37, inwhich each said shaft which runs alongside the transmission is adaptedto be mounted substantially in alignment with or parallel to thelongitudinal axis of the vehicle.
 41. An amphibious vehicle,characterized in that the vehicle comprises a power train as claimed inclaim
 37. 42. A power train for an amphibious vehicle, which power traincomprises an engine adapted for mounting in the vehicle such that acrankshaft of the engine is substantially in alignment with alongitudinal axis of the vehicle, a transmission positioned rearwardlyof the engine, and a power take off positioned in the drive line betweenthe engine and the transmission, the power take off being adapted todrive at least one marine propulsion unit located at the rear of theamphibious vehicle by means of a shaft which runs alongside thetransmission, in which the engine is adapted for mounting towards thefront of the vehicle, and the drive train further includes adifferential driven from the transmission and adapted for mountingbetween the rear wheels of vehicle, the differential being adapted toprovide drive to the rear wheels.
 43. A power train as claimed in claim42, in which the transmission is spaced rearwardly from the engine. 44.A power train as claimed in claim 43, in which the differential isspaced rearwardly from the transmission.